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| author | Richard Henderson <richard.henderson@linaro.org> | 2024-12-08 09:13:45 -0600 |
|---|---|---|
| committer | Richard Henderson <richard.henderson@linaro.org> | 2024-12-24 08:32:15 -0800 |
| commit | 82f898f3b660fb11e601ee5ea1cab4b2fdafacc8 (patch) | |
| tree | 30a43e4d0e4514ebeeadaeaf46e268b2fe2941dc | |
| parent | 72330260cdb42015ae72096bae37e6fdaf361737 (diff) | |
| download | qemu-82f898f3b660fb11e601ee5ea1cab4b2fdafacc8.zip qemu-82f898f3b660fb11e601ee5ea1cab4b2fdafacc8.tar.gz qemu-82f898f3b660fb11e601ee5ea1cab4b2fdafacc8.tar.bz2 | |
softfloat: Add float_muladd_suppress_add_product_zero
Certain Hexagon instructions suppress changes to the result
when the product of fma() is a true zero.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
| -rw-r--r-- | fpu/softfloat-parts.c.inc | 4 | ||||
| -rw-r--r-- | fpu/softfloat.c | 3 | ||||
| -rw-r--r-- | include/fpu/softfloat.h | 5 |
3 files changed, 11 insertions, 1 deletions
diff --git a/fpu/softfloat-parts.c.inc b/fpu/softfloat-parts.c.inc index 37d046c..ebde429 100644 --- a/fpu/softfloat-parts.c.inc +++ b/fpu/softfloat-parts.c.inc @@ -615,7 +615,9 @@ static FloatPartsN *partsN(muladd_scalbn)(FloatPartsN *a, FloatPartsN *b, goto return_normal; } if (c->cls == float_class_zero) { - if (a->sign != c->sign) { + if (flags & float_muladd_suppress_add_product_zero) { + a->sign = c->sign; + } else if (a->sign != c->sign) { goto return_sub_zero; } goto return_zero; diff --git a/fpu/softfloat.c b/fpu/softfloat.c index 6967fb5..8d75d66 100644 --- a/fpu/softfloat.c +++ b/fpu/softfloat.c @@ -2274,6 +2274,9 @@ float32_muladd(float32 xa, float32 xb, float32 xc, int flags, float_status *s) if (unlikely(!can_use_fpu(s))) { goto soft; } + if (unlikely(flags & float_muladd_suppress_add_product_zero)) { + goto soft; + } float32_input_flush3(&ua.s, &ub.s, &uc.s, s); if (unlikely(!f32_is_zon3(ua, ub, uc))) { diff --git a/include/fpu/softfloat.h b/include/fpu/softfloat.h index aa69aec..09a40b4 100644 --- a/include/fpu/softfloat.h +++ b/include/fpu/softfloat.h @@ -120,11 +120,16 @@ bfloat16 bfloat16_squash_input_denormal(bfloat16 a, float_status *status); | Using these differs from negating an input or output before calling | the muladd function in that this means that a NaN doesn't have its | sign bit inverted before it is propagated. +| +| With float_muladd_suppress_add_product_zero, if A or B is zero +| such that the product is a true zero, then return C without addition. +| This preserves the sign of C when C is +/- 0. Used for Hexagon. *----------------------------------------------------------------------------*/ enum { float_muladd_negate_c = 1, float_muladd_negate_product = 2, float_muladd_negate_result = 4, + float_muladd_suppress_add_product_zero = 8, }; /*---------------------------------------------------------------------------- |